Selective Etching in the Formation of Epitaxy Regions in MOS Devices

摘要

A method for forming a semiconductor structure includes forming a gate stack over a semiconductor substrate; forming a recess in the semiconductor substrate and adjacent the gate stack; and performing a selective epitaxial growth to grow a semiconductor material in the recess to form an epitaxy region. After the step of performing the selective epitaxial growth, a selective etch-back is performed to the epitaxy region. The selective etch-back is performed using process gases comprising a first gas for growing the semiconductor material, and a second gas for etching the epitaxy region.

主权项

1. A method comprising:
forming a gate stack over a semiconductor substrate, the semiconductor substrate having a top surface; epitaxially growing a first semiconductor material from exposed surfaces of the semiconductor substrate in a recess of the semiconductor substrate; after the step of epitaxially growing a first semiconductor material, selectively etching-back the first semiconductor material, wherein after the selective etch-back is performed, at least a portion of a top surface of the first semiconductor material is at or above the top surface of the semiconductor substrate; and epitaxially growing a second semiconductor material adjoining the first semiconductor material, the second semiconductor material substantially only growing on the first semiconductor material.